Electronic/magnetic apparatus and method for detecting fluid level

Abstract

A fluid level detector comprises a tank including a sleeve portion extending vertically from a bottom section of the tank to a top section of the tank, and sensor device mounted to a circuit board connected at one end to monitoring device, with the circuit board being inserted into the sleeve. There is a circular float assembly with a center aperture. The circular float assembly includes a pair of magnets mounted in push-pull orientation at opposite sides of the aperture within the float assembly. The float assembly is slidably positioned over the sleeve whereby the float assembly moves up and down the sleeve as the water level changes in the tank, wherein the sensor device generate a signal representing detection of fluid level by the sensor device when the fluid level in the tank is substantially at the level of the sensor device.

What is claimed is: 
     
       1. The method of detecting low fluid level in a tank comprising the steps of a) providing at least one Hall sensor mounted on a circuit board located in a vertical sleeve in the tank;   b) providing a float assembly having first and second identically shaped compartments oriented in one direction at opposite sides of an aperture in said float assembly;   c) inserting a pair of magnets, each of the magnets shaped for matching the shape of said first and second compartments such that said magnets are inserted only in one orientation with the north pole or one of said magnets facing said aperture and the south pole of the other of said magnets facing said aperture;   d) fitting said aperture of said float assembly slidably over said sleeve; and   e) monitoring a signal generated by said Hall sensor when fluid level in the tank causes said float assembly to be substantially next to said Hall sensor.   
     
     
       2. A fluid level detector apparatus, comprising: a tank including a sleeve member extending vertically from a bottom section of said tank to a top section of the tank;   sensor means mounted to a circuit board connected at one end to monitoring means, said circuit board being inserted into said sleeve;   a float assembly included first and second compartments containing a pair of magnets mounted in a push-pull configuration within said float assembly to increase magnetic flux density, said float assembly being slidably positioned over said sleeve member whereby said float assembly moves up and down said sleeve member as fluid level changes in said tank;   wherein said sensor means generate a signal representing detection of the fluid level by said sensor means when the fluid level in the tank is substantially at the level of the sensor means, and wherein said magnets have a particular shape corresponding to a shape of said first and second compartments so that said magnets can be inserted into said compartments in only one orientation to ensure said push-pull configuration.   
     
     
       3. The apparatus according to claim 2 wherein said magnets are plastic molded types. 
     
     
       4. The apparatus according to claim 2 wherein said sleeve member has an asymmetrically shaped interior corresponding to a shape of said circuit board whereby said circuit board is insertable in only one orientation. 
     
     
       5. The apparatus according to claim 4 wherein said sleeve member has an asymmetrically shaped exterior whereby said float assembly can be positioned over said sleeve member is only one orientation. 
     
     
       6. The apparatus according to claim 2 wherein said sensor means comprises at least one Hall switch located near the bottom of said tank for detecting at least low fluid level in said tank, said Hall switch being oriented on said circuit board to detect a signal from said magnets. 
     
     
       7. The apparatus according to claim 6 wherein a second of said Hall switches is located at the top of said tank for detecting a full tank when said tank is being refilled.